The present invention relates to a device for passively reducing the noise vibrations in a liquid resulting from a sound source which is arranged under the liquid level of a body of water, in which the device comprises a noise-insulating pipe which is designed to be arranged around the sound source. The invention also relates to a method for operating such a device.
During activities below the water level of a body of water, for example below the water surface of a sea, river or lake, relatively high noise levels may be generated which can be damaging to animals or humans present in the vicinity. When, for example, ramming has to be carried out underwater, in which case a pile element, such as for example a pile, is driven into the ground by means of a pile-driving device which is situated above water, very high noise levels may occur underwater. As the noise is generated underwater, the sound waves will be audible at a much greater distance from the sound source than would be the case if the sound source were placed above water. In practice, it has been found that during pile-driving work, it is not possible to carry out any other underwater activities in the vicinity, that is to say within a radius of a kilometer or more, which require the use of divers underwater. Other sound sources than a pile, such as, for example, a sonar or an explosive, such as a sea mine, or a cavitating propeller of a vessel can also produce so much noise that this may result in damage to animals and humans in the vicinity of the sound source.